For example, Japanese Patent Application Laid-Open Publication No. 2008-78893 (Patent Document 1) shows a configuration including the pair of the box type switch devices connected to each other via redundancy ports, and the edge switch (box type switch) and the aggregation switch (chassis type switch) which are connected to the pair of box type switch devices. The edge switch is connected to the access port having the same port number in the pair of box type switch devices in the link-aggregation setting state, and the aggregation switch is connected to a network port having the same port number in the pair of box type switch devices in the link-aggregation setting state.